The present invention relates generally to fluid pumping systems and more particularly to heating systems for dual component proportioners.
Fluid proportioners comprise dispensing systems that receive separate inert fluid components, mix the components in a predetermined ratio and then dispense the components as an activated compound. For example, fluid proportioners are used to dispense polyurethanes or polyureas that solidify after mixing of a resin component and an activating material, which are individually inert. After mixing, however, an immediate chemical reaction begins taking place that results in expanded rigid, or non-rigid, plastic foam or a flexible, cured thermoplastic polyurea coating of the mixture. Therefore, the two components are routed separately into the proportioner so that they can remain segregated as long as possible. A manifold receives each component after it is pumped separately and feeds the components to a sprayer including a mixing head that can be actuated by an operator. Thus, the components remain segregated until reaching the sprayer where they are simultaneously mixed and dispensed, thereby minimizing potential for fouling of components.
A typical fluid proportioner comprises a pair of positive displacement component pumps that individually draw in component fluid from separate fluid containers, sometimes with the aid of feed pumps, and pump pressurized component fluids to the manifold. The component pumps are typically driven in synchronicity by a common hydraulic or electric motor. The feed pumps are typically driven by a source of compressed air. The feed pumps and component pumps deliver the component materials to the manifold in a state ready for mixing and dispensing from the sprayer. Specifically, in order to properly trigger the chemical reaction that cures the mixed component materials, the components are often heated to an elevated temperature to reduce and balance the fluid viscosities to ensure proper cross-linking. Typically, the components are heated with electric heaters that heat the material somewhere between the component pumps and the manifold. Such heaters require a supply of external power and therefore reduce the energy efficiency of the system.
Dual component proportioners are sometimes arranged in portable configurations, such as in the cargo area of a truck for completing large-scale jobs at remote job sites. Similarly, these dual component proportioners can be mounted in a trailer pulled behind a vehicle. In such configurations, the proportioner system can be set up to utilize resources of the engine of the truck. For example, coolant from the engine can be used to heat the component materials rather than an electric heater. Likewise, the electrical system of the truck engine can be used to power components of the proportioner. Alternatively, a power take-off from the truck engine can be used to mechanically power various components. However, such embodiments require the engine of the truck to be continuously running while spraying operations are occurring. The truck engine, however, provides excess capacity than what is needed for the proportioner system both in terms of the coolant flow provided by the engine and in terms of mechanical power that is being generated for pumping the coolant or generating electricity. As such, these systems are less efficient than electric heaters. There is, therefore, a need for a more efficient component material heating system, particularly for use with portable proportioner systems.